Conventionally, sealing devices disclosed in Patent Literatures 1 and 2 are known. A sealing device according to the conventional art disclosed in Patent Document 1 will be described herein. The sealing device disclosed in Patent Document 1 is mounted in an inner peripheral surface of a shaft hole of a housing, and seals an annular gap between a rotating shaft and the housing having the shaft hole into which the rotating shaft is inserted. The sealing device includes a metal case, and individual constituent parts of the sealing device are retained by the case and are integrally constructed as a cartridge. In addition, the sealing device includes a sealing member made of rubber (hereinafter referred to as a rubber sealing member) as a primary seal and a sealing member made of resin (hereinafter referred to as a resin sealing member) which has a function as a secondary seal while maintaining the posture of the rubber sealing member.